The EPA sampled 39 wells in 2009 in Pavillion in Fremont County, Wyoming - the site of a natural gas field extracting coal bed methane - after complaints from community members. Samples indicated “high levels”31 of benzene, xylene, and other hydrocarbons like methyl cyclohexane, naphthalene, and phenol. They also found levels of lead, phthalate (a substance found in gelling agents, surfactants, and viscosity adjusters – all used in hydraulic fracturing fluid – that is a
public health concern because it can change hormone levels in humans), and nitrite that were above drinking water standards. EPA re sampled in 2010 and confirmed that this was “highly contaminated shallow groundwater occurring in the same aquifer as drinking water wells.”32 As of the time of the 2010 report, EPA had not yet determined the source
of the contamination. The Wyoming Bureau of Land Management tested well water in Sublette County,
Wyoming, and found benzene levels 1,500 times the acceptable concentration levels. One of the largest natural gas fields in the US is in Sublette, where they extract coal bed methane